1. Field of the Invention
The present invention relates to a vacuum pump and a vacuum apparatus, and more specifically, to a vacuum pump and a vacuum apparatus which can adjust a pressure within a vacuum container.
2. Description of the Related Art
Upon manufacturing a semiconductor or a liquid crystal, in the case where dry etching, CVD, etc., are performed, a vacuum apparatus is used in which a process gas is introduced into a chamber and the process gas is discharged with a vacuum pump.
FIG. 7 shows a turbomolecular pump as an example of the vacuum pump conventionally used.
As shown in FIG. 7, the vacuum pump (turbomolecular pump) has stator blades and rotor blades which are disposed on a stator portion and a rotor portion, respectively, in multistage arrangement in an axial direction. The rotor portion is rotated with a motor at high speed so that the exhaust (vacuum) action is performed from an inlet port side (on the upper side of the drawing) to an outlet port side (on the left and lower side of the drawing).
FIG. 8 shows an outline of the conventional vacuum apparatus in which such a vacuum pump is disposed in relation to a chamber.
As shown in FIG. 8, in the conventional vacuum apparatus, a stage 92 on which a sample 91, etc., are placed is provided within a chamber (container) 90. Also, provided outside the chamber 90 is a drive mechanism 93 for rotating the stage 92 or for performing other functions from the downside of the stage 92. A turbomolecular pump 95 is mounted from the outside of the chamber 90 onto a portion of an outlet port 94 provided at the lower surface (or side surface) of the chamber so as to discharge the gas existing within the chamber 90.
As shown in FIG. 3, in the conventional vacuum apparatus, the outlet port of the chamber 90 and the inlet port of the vacuum pump 95 communicate via a conductance variable valve 96. Accordingly, the amount of process gas to be exhausted from the chamber 90 is adjusted by changing a conductance of the conductance variable valve 96, to thereby control the pressure within the chamber 90 to a predetermined level.
However, in the conventional vacuum apparatus described above, since the conductance variable valve 96 is directly communicated with the exhaust port 94 of the chamber 90, there is a concern that dust produced upon the operation or the like of the conductance variable valve 96 would be caused into flow backward into the chamber 90. The occurrence of dust is an important problem to be particularly avoided in the production of a semiconductor or liquid crystal.
The present invention has been made to solve the above-mentioned problem inherent in the conventional vacuum apparatus, and therefore has a primary object of the invention to provide a vacuum pump in which an adjustment of a suction/discharge force can be made without producing dust,
Further, a secondary object of the present invention is to provide a vacuum apparatus in which an adjustment of a pressure within a vacuum container can be made without producing dust.
In order to attain the primary object of the present invention, there is provided a vacuum pump, comprising: an inlet port for sucking a first gas from outside; a gas feed section for feeding the first gas sucked from the inlet port; an outlet port for discharging the gas within the gas feed section; a pressure changing means for changing the pressure within the gas feed section; and a control means for controlling the change of pressure changed by the pressure changing means.
According to the vacuum pump of the present invention, the pressure within the gas feed section can be changed with the pressure changing means, thereby being capable of changing a suction force for sucking gas from the inlet port. Accordingly, an adjustment of the suction force for sucking gas can be made without providing a valve between the container from which the gas is to be sucked. As a result, contamination of the container by dust occurring from the valve can be avoided.
The vacuum pump of the present invention may employ such a structure that the pressure changing means includes a gas mixing means for mixing a second gas with the first gas that is feeding at the gas feed section, and the control means controls the amount of the second gas mixed by the gas mixing means.
In addition, the vacuum pump of the present invention may employ such a structure that it further comprises an auxiliary pump for sucking the first gas discharged from the outlet port, wherein the pressure changing means includes a conductance variable valve provided between the outlet port and the auxiliary pump, and the control means controls a conductance of the conductance variable valve.
In order to attain the secondary object of the present invention, according to the present invention, there is provided a vacuum apparatus, comprising: the vacuum pump; and the container from which the gas is to be sucked and discharged with the vacuum pump.
In this case, it preferably has a structure in which the vacuum apparatus further comprises a pressure sensor for detecting the pressure within the container, and the control means decides an amount to be controlled in accordance with an output from the pressure sensor.